In our criminal-justice system, once a person has been convicted, no matter how shaky the conviction, the presumption of innocence disappears. The defendant is assumed to have had a fair trial. New evidence, even enough to sow a field of doubt, does not necessarily entitle a defendant, not even one on death row, to a new trial. The remarkable defense attorney Diana Holt learned these lessons the hard way after she took on the case of Richard Charles Johnson, in October of 1999.

Holt, then 41, had worked as an attorney at the Center for Capital Litigation, in South Carolina, a nonprofit that represented prisoners on death row. Blond, blue-eyed, physically slight, and intense, Holt had begun working at the center a few years earlier, while still in law school. Having overcome great hardships in her own life, she had acquired a singular reputation as somebody who would work indefatigably to save the lives of the condemned—which is why her former mentor at the center, John Blume, asked her to help with the Johnson case. She would work on it for the next three years.

The case dated back to September 27, 1985, when Johnson, a 22-year-old knockabout, hitched a ride outside Morehead City, North Carolina, with Daniel Swanson, a 52-year-old real-estate developer from suburban Washington, D.C. Swanson owned an RV, had a fondness for pornography, and was en route to Florida. The two soon stopped in South Carolina and picked up a couple of other hitchhikers: Curtis Harbert, a 20-year-old on the run after having stolen a car, and his companion, Connie Sue Hess, a 17-year-old who was into drugs and sex with truckers.

Travels With Charley it wasn’t. There was alcohol, lots of it, and a variety of drugs. In due course, Harbert, Hess, and Swanson ended up in bed together in the rear of the RV—at which point somebody shot Swanson in the back of the head.

After hiding Swanson’s body under a mattress in the RV, Harbert, Hess, and Johnson continued south, with Johnson at the wheel. Wiped out on drugs and booze, he wove all over the road, bouncing off guardrails, while Hess put on a show for passing truckers, rubbing her breasts up against the RV’s rear window. After a state trooper named Bruce Smalls pulled them over and began walking toward the RV, a door opened. Smalls stepped up to the door, and shots were fired at him. Leaving Smalls dead on the side of the highway, Johnson fled in one direction, Harbert and Hess in another. All were quickly caught.

Under questioning that night, Hess told the police that Johnson had killed both Swanson and Smalls. The next day, however, she changed her story, claiming that Harbert had shot both men. Two days later, still in police custody, she returned to her original story, which Curtis Harbert corroborated. At Johnson’s trial, the state didn’t call Hess, perhaps uncertain of what she would say on the stand, given her prior inconsistent statements. Foolishly, however, the defense did, and she fingered Johnson.

In separate cases, the state charged Johnson with the murders of Swanson and Smalls. Johnson pleaded guilty in the former case but not the latter. Investigators had found no gunpowder residue or other physical evidence implicating him in the murder of Bruce Smalls, but Hess’s and Harbert’s testimony helped sway the jury, which found Johnson guilty as charged. The murder of a police officer is a capital offense in South Carolina, a staunch death-penalty state that has been executing criminals since it was a colony, and the outcome was therefore inevitable: Johnson was sentenced to death.

So began a saga that would drag on for years, as so many death-penalty cases do. Initially, Johnson had cause for hope. In 1987, on appeal, the South Carolina Supreme Court overturned his conviction for the murder of Bruce Smalls, because the prosecutor in the case had made improper comments during his closing argument. But the reprieve didn’t last long. In 1988 the state tried him again and won another conviction. Once again, Johnson was sentenced to death.

Diana Holt took on the case 11 years later.

Her career path had been indirect, to say the least. Born in El Paso, Texas, in 1958, she had endured a harrowing childhood. For years her stepfather, Walter Belshaw, abused her sexually. As best she can remember, it started when she was 3 or 4. Her mother was about 20, Belshaw about twice that age. “If you want some milk,” she remembers him saying, “put your mouth here.”

Not surprisingly, given the circumstances, Holt didn’t do well in school, but nonetheless, in the sixth grade she decided she wanted to be a lawyer. Her stepfather mocked her ambitions. When he began teaching her to drive, he fondled her, saying that was what boys would do. He gave her drugs, entertained her at swanky bars, and took pictures of her naked. At the age of 17 she ran off with strangers and ended up in New Orleans, where an incident took place that she would keep secret for years, even from her closest friends and family. Nearly three years after she ran away from home, Holt returned to Texas, got married, got divorced, got pregnant, and then got married again—this time to an angry Vietnam vet who, Holt told the police, tried to kill her after an argument. (Only a defective firing pin in his revolver saved her life.) Holt divorced him and pressed charges, but the state declined to prosecute, telling her that it boiled down to her word against his, which simply wasn’t good enough. That he wasn’t even charged with a crime outraged Holt. The moment was a turning point for her. She decided to act on her sixth-grade dream and become a lawyer.

In 1986, Holt began taking courses at community college. She quickly revealed herself to be both smart and disciplined. After four semesters of straight A’s, she enrolled at Southwest Texas State University. She had recently married again and was pregnant with her third son, but still she managed to get straight A’s, to make the dean’s list every semester, and to graduate summa cum laude. She applied to law school, without much hope that she’d get in, given her past, but the University of Texas admitted her, in 1991. There, influenced by a couple of her professors, she became committed to representing men and women on death row.

In the world of appellate criminal defenders, “law lawyers” are ardent students of the Constitution, and of the Supreme Court cases interpreting it. In death-penalty cases, they might argue that their clients did not get a fair trial or were denied effective assistance of counsel; that the state failed to hand over exonerating evidence; that jury selection was biased; that constitutional provisions were violated. “Fact lawyers,” on the other hand, are those who search for evidence that either proves their clients did not commit the crime or, if they did, alters the details of the case significantly enough to spare their lives. By 1999, Holt had become a fact lawyer extraordinaire, an investigator’s investigator. No matter how deeply evidence was buried, she could find it. She also had an uncanny ability to get people to open up to her, and even to confess to murder, perhaps because of her diminutive size, which put them off guard, or because of her southern drawl, which would thicken noticeably when she felt it would help her gain somebody’s confidence.

Holt’s signature case—one of the first she ever took on, in 1993—involved Edward Lee Elmore. An African American, Elmore was on death row for the 1982 murder of Dorothy Ely Edwards, a wealthy white widow from Greenwood, South Carolina. The case brought together a remarkable number of the elements that make the capital-punishment debate so fraught today: questions of racial bias, mental retardation, ineffective assistance of trial counsel, contaminated evidence, withheld evidence, prosecutorial misconduct, a strong claim of innocence, and more. Edwards’s battered and bloodied body had been found in her bedroom closet. Within 48 hours, Elmore, a semiliterate handyman who had washed windows at her house a few weeks before the murder, had been arrested and charged with the crime, and 90 days later, after a trial lasting only eight days, he had been sentenced to death.

Elmore’s lawyers had put up virtually no defense. The prosecutor at the trial, William T. Jones III, a legendary figure in South Carolina, told the judge he had authorized Elmore’s arrest after a police officer informed him that a “Negroid” hair had been found on the victim’s abdomen during the autopsy. The prosecution didn’t introduce the hair into evidence, and it seemed to have disappeared, until 11 years later, when Holt and her co-counsel in the case, J. Christopher Jensen, a highly accomplished litigator from New York who was working pro bono, began doggedly searching for it. Eventually the hair turned up in a filing cabinet belonging to the very investigator who had examined it in 1982. The state attorney general’s office concluded that the hair had been there all along while state investigators had been saying it couldn’t be found. When an independent investigator hired by the state subsequently examined the hair, he found that it belonged to a Caucasian and called the state’s earlier finding “a fraud.”

During a lull in the Elmore case, Holt took on the Johnson appeal. Time was of the essence: Johnson’s execution was scheduled for the end of the month. John Blume asked Holt to track down witnesses, including Connie Sue Hess, the young hitchhiker who had accused Johnson of murdering Daniel Swanson. And less than two weeks before the execution date, she found her, in Norfolk, Nebraska, spending her days at a facility designed to help people recovering from mental illness reintegrate into the community. Holt traveled to Norfolk and interviewed Hess, who eventually admitted to Holt that she had killed Smalls. “There you go, bastard!,” she recalled shouting at Smalls after shooting him. When Holt pressed her about why she had lied at the time of her arrest, her answer was simple: the prosecutor had told her she would “fry” if she’d had anything to do with the murder. But she was telling the truth now, she insisted, because she couldn’t let Johnson be executed for something he hadn’t done.

Stunned by Hess’s confession, Holt drafted an affidavit for Hess to review, had her sign it in front of a notary (and a lawyer representing Hess, who advised her not to sign it), and then raced back to South Carolina to show it to Blume, who was the lead attorney on the case. With less than a week to go before Johnson was to be executed, Blume petitioned the South Carolina Supreme Court for a stay. The court hadn’t issued a last-minute stay in decades, but now, confronted with Hess’s sworn testimony, it did so—less than 24 hours before Johnson was to be strapped to the gurney—and assigned a judge, William P. Keesley, to conduct a hearing.

The state was not happy. Holt was proving to be a thorn in its side. In the Elmore case, she and Jensen had discovered exonerating evidence that, they claimed, the state had improperly withheld—not only the so-called Negroid hair but also a fingerprint on the underside of the toilet seat in the victim’s bathroom that didn’t belong to Elmore or the victim. They had also suggested that the state had planted evidence in the case, which the state denied. Now Holt’s work had helped stall an execution and had persuaded the state supreme court to order a potentially embarrassing hearing. OTo fight back, the state decided to attack her reputation.

Holt had a secret that made her vulnerable: a run-in with the law she’d had decades before, in New Orleans. With one exception, none of her closest friends knew about it, nor did her sons.

It had happened in 1975, when Holt was 17. During the custody battle that had followed her mother’s divorce from Walter Belshaw, she had been made to testify about the abuse she’d suffered at his hands, and then had had to sit by as scores of photographs of her posing in the nude had been introduced into evidence, and as her stepfather’s lawyer had accused her of lying about the abuse. The experience traumatized her. Feeling lost, abandoned, and unloved, she fell in with an unsavory set of new friends, ran away from home, and ended up with them in New Orleans. After three days of partying, they ran out of money. Holt’s companions came up with a plan to replenish their supply: she would go to the French Quarter, pick somebody up, and lure him away from the crowds, at which point one of her companions would rob him.

It didn’t go as they’d hoped. Wearing a schoolgirl dress, Holt took a seat outside at a restaurant, ordered a Tom Collins, and began flirting with a man a few tables over. Later, as they were getting into the man’s car, Holt’s accomplice rushed over, held a gun to the man’s temple, and robbed him of $61 and a 9-mm pistol that he had under the seat. Unfortunately for Holt and her friend, the man turned out to be a U.S. marshal. The two were caught before they had run two blocks.

Holt pleaded guilty to armed robbery, a felony offense, and was sentenced to five years, although she was told that with good behavior she would be out in two years, eight months, 21 days—numbers she would never forget. She was sent to the Louisiana Correctional Institute for Women, in St. Gabriel, and became Prisoner 80367.

In prison, Holt matured, got off drugs, and learned a lot. She realized how close she had come to going over the edge. She met as equals the types of people most lawyers meet only as clients. Above all, she developed a strong capacity for empathy. Prison officials, impressed by her exemplary behavior, took a liking to her. They believed in rehabilitation, and she was showing promise. Gradually, she became their prize exhibit. Young, gentle-looking, and more educated than most of her fellow inmates, she was sent by the prison to speak to sociology and criminology classes at Louisiana State University and, in 1976, to the Louisiana Governor’s Conference on Women. A photo taken at the conference shows her with long hair, a low-cut dress, and a white necklace. Anybody might have mistaken her for a fun-loving coed.

In 1977, thanks to her good behavior in prison, Holt received a pardon and was released on October 30. Years later, Texas, South Carolina, and Georgia all deemed her to be of sufficient moral character to practice law. She could now leave the whole tawdry episode behind. Or so she thought until the Johnson case—when, after she had produced Connie Sue Hess’s confession and forced a hearing, the South Carolina attorney general’s office decided to use her conviction against her.

Donald Zelenka, the head of the capital-cases section in the attorney general’s office, knew that Hess would be called to testify as part of the hearing. If she declined—which he knew she well might, given the criminal charges she could face for admitting to having taken part in the Smalls murder—the defense would then have to introduce Hess’s notarized affidavit into evidence. Holt, in turn, would have to take the stand to vouch for the affidavit’s authenticity, at which point Zelenka could try to expose her as a convicted felon, in an effort to undermine her testimony.

Zelenka deposed Holt on April 21, 2000. During the course of the deposition, he produced not just photocopies of the Louisiana police’s investigative report on Holt’s arrest but carbon copies obtained directly from the files. (He never explained how he acquired them, and has repeatedly denied my requests for an interview.) With the report in front of him, Zelenka then proceeded to question Holt for several hours about her conviction and her personal history. Based on the information he extracted during that deposition and from the police report, he then prepared a 30-page memorandum portraying her, in effect, as trailer-park trash.

The strategy failed. Visibly disgusted with the state’s behavior, Judge Keesley refused to allow Zelenka to use the information to impeach Holt. The ruling came as a tremendous relief to Holt for personal reasons, but it represented only a small and temporary victory in the case, because the South Carolina Supreme Court later went on to reject Johnson’s appeal. To get a new trial, the court declared, the defendant would have to show that the new evidence (in this case, Hess’s sworn confession) would “probably change the result” of the original trial—a standard that had not yet been met. “We do not believe it is probable,” Justice James E. Moore wrote for the majority, that “a jury would find Hess credible given her prior inconsistent statements.”

The dissents were short but powerful. “I believe that to deny Johnson a new trial in the face of a confession by someone who was admittedly present when the murder was committed would constitute ‘a denial of fundamental fairness shocking to the universal sense of justice,’” Justice John H. Waller Jr. wrote in a three-paragraph opinion, citing an earlier U.S. Supreme Court decision. Continuing in his own words, he added, “Our system of justice dictates that before Johnson is put to death he must be given an opportunity to present such evidence to a jury of his peers.”

The final legal recourse available to Blume and Holt was an appeal to the United States Supreme Court. This would be an uphill battle, they knew, in part because of how the Court had ruled seven years earlier in Herrera v.Collins.

That case concerned Leonel Torres Herrera, a drug dealer on death row in connection with the murder of two Texas police officers. Ten years after Herrera had been convicted, his attorneys produced evidence that his brother, Raul (since deceased), had confessed that he, not Leonel, had killed the officers. Raul’s oldest son also swore that he had seen his father kill the officers. Based on these statements, Herrera sought a new trial, but the Court ruled that he had no right to one. Federal courts, then–Chief Justice William Rehnquist wrote, “sit to ensure that individuals are not imprisoned in violation of the Constitution—not to correct errors of fact.” After a defendant has had a fair trial, he continued, the presumption of innocence disappears. In order to get a new trial, a convicted person—even a demonstrably innocent one—has to establish that one of his constitutional rights has been violated. Rehnquist’s argument boiled down to a simple idea: the need for finality in legal proceedings can sometimes trump fairness. Quoting a 1977 Supreme Court decision, he wrote, “‘Due process does not require that every conceivable step be taken, at whatever cost, to eliminate the possibility of convicting an innocent person.’” He continued, “To conclude otherwise would all but paralyze our system for enforcement of the criminal law.”

Justice Harry Blackmun dissented. “I believe it contrary to any standard of decency to execute someone who is actually innocent,” he wrote. “The execution of a person who can show that he is innocent comes perilously close to simple murder.” Justices John Paul Stevens and David Souter joined Blackmun in the dissent. Justice Antonin Scalia, concurring with the majority, scoffed that the dissenters were letting personal opinion interfere with legal reasoning. If the majority decision offended their consciences, he suggested, “perhaps they should doubt the calibration of their consciences or, better still, the usefulness of ‘conscience shocking’ as a legal test.” Leonel Herrera was executed four months later.

Herrera was a legal hurdle that Holt and Blume knew they would have a hard time getting past—and, indeed, the Supreme Court ended up declining to hear Johnson’s case. Only one option now remained that might save Johnson’s life: an appeal for clemency to James Hodges, the governor of South Carolina. But here, too, the odds were very long. Since the death penalty had been reinstated, in 1977, no South Carolina governor had granted clemency. And this was an election year. Hodges, a Democrat, faced a potential challenge from the state’s Republican attorney general, Charlie Condon, a staunch death-penalty proponent, who had once remarked that the electric chair should be replaced by an electric couch. To win reelection, Hodges had to come across as a strong death-penalty proponent himself—and so, predictably, he refused clemency. The execution of Richard Charles Johnson would take place after all, on May 3, 2002.

Lethal injection was first proposed as a method of execution in the 19th century, by a New York doctor who argued that it would be cheaper than hanging. The idea went nowhere until 1977, when Oklahoma adopted the practice. All the other capital-punishment states followed suit. The procedure involves strapping the condemned prisoner onto a gurney and wheeling him into an execution chamber, where witnesses behind one-way glass can observe the proceedings. His arms are swabbed with alcohol, and two intravenous tubes are inserted, one in each arm. From another room, an invisible executioner starts the flow of a general anesthetic into the tubes (for surgery, 100 to 150 milligrams of it is used; for executions, as much as 5,000 milligrams), followed by a muscle relaxant, which paralyzes the diaphragm and lungs, rendering breathing impossible. Finally, potassium chloride may be injected, causing death by cardiac arrest.

The proponents of lethal injection have long made the case for it as the most humane method of execution available. Over the years, opponents have mounted systematic challenges to the practice, arguing that because the drugs involved can be improperly administered, it violates the Eighth Amendment of the Constitution, which prohibits cruel and unusual punishment. In 2008, in the case of Baze v.Rees, the Supreme Court finally ruled on the practice, pronouncing it legal. The Court, wrote Chief Justice John Roberts in the majority opinion, had consistently rejected challenges to methods of execution ever since 1879, when it had upheld use of the firing squad. “Our society has nonetheless steadily moved to more humane methods of carrying out capital punishment,” he noted. “The firing squad, hanging, the electric chair, and the gas chamber have each in turn given way to more humane methods, culminating in today’s consensus on lethal injection.”

In the days leading up to his execution, Holt talked to Johnson almost daily, convinced, then as now, that he was innocent of the murder of Bruce Smalls. On execution day, she spent almost seven hours with him in a small cell outside the death chamber, where she found him smoking cigarette after cigarette, wildly talkative at times and somber at others. With the hour of his execution almost upon him, he ate his last meal (fried shrimp, fried oysters, French fries, chocolate cake, and iced tea), and then, at 6:18 p.m., at the age of 39, he was put to death. At his funeral, before the casket was closed, his sister managed to cut some locks of his hair. A few days later, she and Holt went to a North Carolina beach that he’d loved, waded into the surf, and let them go.

The Johnson case hardened Holt’s opposition to the death penalty and strengthened her resolve to win a new trial for Edward Lee Elmore. There was some cause for hope: DNA testing revealed that the Caucasian hair found on the body of Dorothy Edwards was not her own, raising the possibility of a white killer. That alone seemed sufficient to warrant a new trial for Elmore, but the judge in the case ruled otherwise. “One hair,” he declared, “is not enough.” Last November, however, more than 18 years after Holt first started working on the Elmore case, the U.S. Court of Appeals for the Fourth Circuit, in Richmond, Virginia, ruled 2–1 that Elmore was indeed entitled to a new trial. The senior justice on the bench dissented strongly, however, and the State of South Carolina has already declared its plans to appeal.

Holt has strong personal opinions about Johnson’s and Elmore’s innocence. At root, though, her objection to the death penalty isn’t so much moral as it is practical. “There is no way to implement it fairly,” she says. “Despite all legal safeguards, whether one gets death or not is dependent on geography, the elected official with the power to seek it, the color of his skin, gender, the color of the victim’s skin, the victim’s gender, wealth of any of those, poverty of the defendant, mental health of any of those, and judges with agendas”—not to mention, she continues, “the integrity of law enforcement, the competence of law enforcement, the competence of forensic analysts, and on and on.”

These are the sorts of factors that, in January of 2003, famously led the governor of Illinois, George Ryan, to make the extraordinary move of commuting the sentences of 167 death-row inmates on a single day. It was a monumental step, all the more so because as a legislator, in 1977, Ryan had voted to reinstate the death penalty. Ryan made his announcement at Northwestern University Law School, where a joint clinic with the journalism school had recently resulted in several men’s release from death row. Ryan told his audience that when he had become governor, in 1999, he had strongly supported the death penalty. “I believed,” he recalled, “that the ultimate penalty for the taking of a life was administered in a just and fair manner.” But now he wasn’t so sure, not in light of the work recently done by the clinic at Northwestern—and certainly not in light of “the systematic failures of our capital-punishment system,” as he put it, that had recently been revealed in a landmark series of articles published by the Chicago Tribune. Two of the paper’s reporters, Steve Mills and Ken Armstrong, had closely examined some 300 capital cases in Illinois and discovered that nearly half of them had been reversed on appeal.

To Ryan, that just didn’t seem right. “Now, how many of you people here today that are professionals can get by and call your life a success if you’re only 50 percent successful?” he asked rhetorically. More than two-thirds of the inmates on death row in Illinois were African American, he continued—a wildly disproportionate number that made a mockery of any pretense to fairness. The death penalty, Ryan reminded his audience, had been abolished by every European country, along with Canada, South Africa, and most countries in Latin America. This, he said, made the United States “partners in death with several Third World countries.”

Winding down his speech, Ryan borrowed much-quoted language from Justice Blackmun, who, in 1994, at the end of his career, had announced that under no circumstances could he consider the death penalty constitutional. Quoting Blackmun, Ryan said, “‘I no longer shall tinker with the machinery of death.’” The Illinois legislature banned the death penalty in 2011.

New Jersey, New Mexico, and New York have all done the same in recent years, and this past November the governor of Oregon, John Kitzhaber, declared that during his time in office he would allow no more executions to be carried out in his state, calling the system of death-penalty justice “compromised and inequitable.” As governor he had already authorized two executions. These were decisions he had come to regret. “I do not believe that those executions made us safer,” he said; “certainly I don’t believe they made us more noble as a society. And I certainly cannot participate once again in something I believe to be morally wrong.”

Diana Holt takes heart from these changes. But 34 states, along with the federal government and the U.S. military, continue to allow capital punishment, and American public opinion still tilts in its favor.